Propulsion assembly for an aircraft comprising a turbojet engine, a pylon and means for attaching the turbojet engine to the pylon

Abstract

The invention relates to an aircraft propulsion assembly (100) having a turbojet engine comprising a casing (112) and a propeller (53), a mounting pylon (104) with a front arch (108) with two extensions (108b) which extend around the casing (112) over at least 90°, a central connecting rod (120) having a rear end (120a) articulated to the mounting pylon (104) and a front end (120b) articulated to the casing (112), and two lateral connecting rods (122), where each inner connecting rod (122) has a rear end (122a) articulated to the extension (108b) which is on the same side of the median plane (P) and a front end (122b) articulated to the casing (112) and where the longitudinal axes of the lateral connecting rods (122) and of the connecting rod central (120) converge on a longitudinal axis (X) at the center of the propeller (53). With such an arrangement, the moments generated in the propulsion unit are applied at the center of the propeller and therefore do not overload the engine casing.

Description

TECHNICAL FIELD

[0001] The present invention relates to the general field of attaching a turbojet engine under the wing of an aircraft. It relates in particular to a propulsion unit comprising a turbojet engine, for example of the unducted fan turbojet engine type, a mast and a attachment assembly intended for attaching the turbojet engine under the mast. It also relates to an aircraft equipped with such a propulsion unit. STATE OF THE PRIOR ART

[0002] An aircraft typically comprises wings and at least one propulsion unit attached under each of these wings. Each propulsion unit comprises a pylon and an engine. The pylon has a rigid structure called the "primary structure" which is attached between the wing and the engine by means of attachment assemblies, namely a first attachment assembly between the wing and the pylon and a second attachment assembly between the pylon and the engine.

[0003] Although such an engine assembly is efficient, the evolution of turbojets leads to the need to develop mounting pylons which, among other things, make it possible to minimize the forces between the turbojet, the mounting pylon and the wing, and in particular the torsional forces of the engine casing. STATEMENT OF THE INVENTION

[0004] An object of the present invention is to provide a propulsion unit comprising a turbojet engine, a mast and a hooking device intended for hooking the turbojet engine under the mast, and which makes it possible, among other things, to minimize the torsional forces of the engine casing. To this end, a propulsion unit of an aircraft is provided, said propulsion unit having a longitudinal axis and a vertical median plane passing through the longitudinal axis and comprising: a turbojet engine comprising a casing around the longitudinal axis and a propeller at the front of the casing, where the longitudinal axis constitutes the axis of rotation of the propeller, a mounting pylon having a primary structure and a front arch having a central part secured to the primary structure and on either side of the central part relative to the median plane, two extensions which extend around the casing over at least 90°, a central connecting rod arranged at the median plane, where the central connecting rod has a rear end mounted articulated to the mounting pylon by a first rear connection point and a front end mounted articulated to the casing by a first front connection point, and two lateral connecting rods arranged on either side of the median plane,where each inner connecting rod has a rear end mounted hinged to the extension which is on the same side of the median plane by a second rear connection point and a front end mounted hinged to the casing by a second front connection point and where the longitudinal axes of the lateral connecting rods and the central connecting rod converge on the longitudinal axis at the level of the center of the propeller, and a rear engine attachment fixing the primary structure to a rear part of the casing.

[0005] With such an arrangement, the moments generated in the propulsion unit are applied at the center of the propeller and therefore do not overload the engine casing.

[0006] Advantageously, the second front connecting points of the side connecting rods are arranged at 90°±20° around the longitudinal axis from the first front connecting point of the central connecting rod.

[0007] Advantageously, the second front connecting points of the side connecting rods are arranged at 130°±20° around the longitudinal axis from the first front connecting point of the central connecting rod.

[0008] Advantageously, the propulsion unit includes a rear engine attachment which ensures the attachment of the attachment mast to a rear part of the casing.

[0009] The invention also proposes an aircraft comprising a wing and a propulsion unit according to one of the preceding variants, the primary structure of which is fixed under the wing. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The above-mentioned and other features of the invention will become more clearly apparent from the following description of an exemplary embodiment, said description being given in relation to the accompanying drawings, among which: Fig. 1 represents a side view of an aircraft according to the invention, Fig. 2 is a schematic representation in side view of a propulsion unit according to a first embodiment of the invention, Fig. 3 is a schematic representation in front view of the propulsion unit according to the first embodiment of the invention, Fig. 4 is a schematic representation in side view of a propulsion unit according to a second embodiment of the invention, Fig. 5 is a schematic representation in front view of the propulsion unit according to the second embodiment of the invention, and Fig. 6 is a schematic representation in rear view of a propulsion unit according to the invention. DETAILED PRESENTATION OF EMBODIMENT METHODS

[0011] In reference to the Fig. 1 , an aircraft 50 comprises a fuselage 51 to which is fixed, on each side, a wing 52 under which is mounted at least one propulsion unit 100 according to the invention.

[0012] The propulsion unit 100 comprises a mounting pylon 104 fixed under the wing 52 and a turbojet engine 102 fixed under the mounting pylon 104. The turbojet engine 102 is here of the turbojet engine type with an unducted fan but it can also take the form of a dual-flow turbojet engine where the fan is ducted. Generally speaking, the turbojet engine 102 comprises a propeller 53 or a fan that can rotate about a longitudinal axis X. In the present application, the term “propeller” encompasses both a propeller and a fan.

[0013] By convention, the longitudinal axis of the turbojet engine 102 and therefore of the propulsion unit 100 is called X, this longitudinal axis X being parallel to a longitudinal direction of this turbojet engine 102. On the other hand, the transverse axis of the turbojet engine 102 which is horizontal when the aircraft is on the ground is called Y, and the vertical axis or vertical height when the aircraft is on the ground is called Z, these three directions X, Y and Z being orthogonal to each other.

[0014] On the other hand, the terms "front" and "rear" are to be considered in relation to a direction of advance of the aircraft 50 during operation of the turbojet 102, this direction being represented schematically by the arrow 107 on the Fig. 1 .

[0015] THE Figs. 2 And 3 show the propulsion assembly 100 according to a first embodiment of the invention and the Figs. 4 And 5show the propulsion assembly 100 according to a second embodiment of the invention.

[0016] The turbojet engine 102 comprises, from front to rear, a propeller 53, a nacelle 54 in which the other elements of the turbojet engine 102 are housed and which take the form of a core having a casing 112 in which the other elements of the turbojet engine 102 are housed as from front to rear compression stages, a combustion chamber, turbine stages and an ejection cone. The casing 112 is coaxial with the longitudinal axis X which constitutes an axis of rotation of the turbojet engine 102.

[0017] The attachment mast 104 is represented here by its primary structure 106 which is fixed to the structure of the wing 52 by any appropriate securing means known to those skilled in the art.

[0018] The primary structure 106 is in the form of a box extending in the longitudinal direction X and which comprises a front wall 106e, located at the front of the primary structure 106, a lower spar 106a extending below the primary structure 106 and an upper spar 106b extending above the primary structure 106. The primary structure 106 also comprises two side walls 106c-d on each side of a vertical median plane P. These different spars and walls are fixed to each other to form the primary structure 106.

[0019] The attachment pylon 104 and the turbojet engine 102 are generally symmetrical with respect to a vertical median plane XZ of the propulsion unit 100 which passes through the longitudinal axis X, which is called here median plane P and which separates the attachment pylon 104 and the turbojet engine 102 into two port-starboard parts.

[0020] The attachment mast 104 also comprises a front arch 108 having a central portion 108a and two extensions 108b which are integral with the central portion 108a. The central portion 108a is integral with the primary structure 106, and more particularly with the front wall 106e or constitutes a part of the front wall 106e. The central portion 108a extends on either side of the median plane P. The two extensions 108b are arranged on either side of the central portion 108a relative to the median plane P, and they extend around the casing 112 over at least 90° from the upper portion of the casing 112, that is to say over at least 180° from one side to the other passing through the top. In other words, in front view, the extensions 108b extend at least to 3 o'clock on one side and 9 o'clock on the other side, that is to say respectively preferably between 3 o'clock and 5 o'clock, and between 7 o'clock and 9 o'clock.

[0021] The propulsion assembly 100 also comprises a central connecting rod 120 which is arranged at the level of the median plane P. The central connecting rod 120 has a rear end 120a which is mounted articulated to the attachment mast 104 by a first rear connection point and a front end 120b which is mounted articulated to the casing 112 by a first front connection point. The attachment to the attachment mast 104 is carried out at the level of the central part 108a or the front wall 106e.

[0022] The propulsion assembly 100 also comprises two lateral connecting rods 122 and 124 which are arranged on either side of the median plane P. Each lateral connecting rod 122, 124 has a rear end 122a, 124a which is mounted articulated to the extension 108b which is on the same side of the median plane P by a second rear connection point and a front end 122b, 124b which is mounted articulated to the casing 112 by a second front connection point.

[0023] Each lateral connecting rod 122, 124 and the central connecting rod 120 has a longitudinal axis which extends between its two ends and which are here represented by the axis lines referenced respectively 52, 54 and 50. On the Fig. 2 , the longitudinal axis 52 of the lateral connecting rod 122 merges with the longitudinal axis X. According to the invention, the longitudinal axes 50, 52 and 54 of the lateral connecting rods 122 and 124 and of the central connecting rod 120 converge on the longitudinal axis X at the center of the propeller 53.

[0024] Such an arrangement makes it possible to apply the moments generated in the propulsion assembly 100 at the level of the center of the propeller 53 while therefore not overloading the casing 112.

[0025] In the embodiments of the invention, to complete the attachment of the turbojet 102 to the attachment pylon 104, the propulsion assembly 100 comprises a rear engine attachment 150 which attaches the primary structure 106, and more particularly the lower spar 106a and a rear part of the casing 112 which is at the rear relative to the lateral connecting rods 122 and 124 and to the central connecting rod 120. Such a rear engine attachment 150 ensures the transfer of the inertial forces from the casing 112 to the attachment pylon 104.

[0026] There Fig. 6 shows a particular embodiment of the rear engine attachment 150.

[0027] The rear engine attachment 150 here comprises a first connecting rod 152a and a second connecting rod 152b which are arranged on either side of the median plane P and inscribed in a plane perpendicular to the longitudinal axis X. One of the connecting rods 152a, here the starboard one, is mounted articulated by a first connection point to the lower spar 106a and by a second connection point to the casing 112, and the other connecting rod 152b, here the port one, is mounted articulated by a third and a fourth connection point to the lower spar 106a and by a fifth connection point to the casing 112.

[0028] Here, the first, second, third, fourth and fifth connection points each take the form of a clevis-type connection, where the axes of the clevis connections are here parallel to the longitudinal axis X.

[0029] The solution has the advantage of being able to keep a support, here the rear engine attachment 150, at the rear at the level of the turbine present in the casing 112 which ensures better overall stability (for example, for the inertial loading of the turbojet, dynamic stability, etc.) and better safety (for example, sensitivity to engine surges), while limiting the flexing of the casing 112, which has an impact on the management of functional clearances.

[0030] As before, the connection points of the lateral connecting rods 122 and 124 and the central connecting rod 120 also take the form of a clevis-type connection, preferably ball-jointed. For reasons of redundancy, each connecting rod is doubled. Thus, each connecting rod consists of two sub-connecting rods joined to each other and where the two sub-connecting rods have the same connection points.

[0031] In the first embodiment of the invention, the second front connecting points 122b and 124b of the side rods 122 and 124 are arranged at 90°±20° around the longitudinal axis X from the first front connecting point of the central rod 120 which is at 12 o'clock. Thus, here, the second front connecting point 122b which is on the starboard side is at 90°±20° clockwise around the longitudinal axis X in front view and the second front connecting point 124b which is on the port side is at 90°±20° counterclockwise around the longitudinal axis X in front view. The 90° angles are shown in the Fig. 3 .

[0032] Of course, depending on the position of the second connecting points before 122b, 124b, the extensions 108b will extend accordingly.

[0033] In the second embodiment of the invention, the extensions 108b go completely around the casing 112. The front arch 108 thus takes the form of a ring which surrounds a portion of the casing 112.

[0034] Here, the second forward connecting points 122b and 124b of the side rods 122 and 124 are arranged at 130°±20° around the longitudinal axis X from the first forward connecting point of the central rod 120 which is at 12 o'clock. Thus, here, the second forward connecting point 122b which is on the starboard side is at 130°±20° clockwise around the longitudinal axis X in front view and the second forward connecting point 124b which is on the port side is at 130°±20° counterclockwise around the longitudinal axis X in front view. The 130° angles are shown in the Fig. 5 .

[0035] Of course, in this second embodiment, the extensions 108b can go less far than the complete turn of the casing 112.

[0036] In the examples disclosed below, the turbojet engine mounting system 102 is a statically determined six-degree-of-freedom system, including one degree of freedom attributable to the central connecting rod 120, one additional degree of freedom attributable to each lateral connecting rod 122, 124, and three degrees of freedom attributable to the rear engine mount 150. The central connecting rod 120 distributes the aerodynamic loads along the longitudinal axis X and the vertical axis Z. The lateral connecting rods 122 and 124 distribute the aerodynamic loads along the longitudinal axis X and the transverse axis Y. The rear engine mount 150 distributes the aerodynamic loads along the transverse axis Y and the vertical axis Z as well as the moments Mx, My and Mz created by the turbojet engine 102 by cooperation / coupling with the front planar interfaces provided by the central connecting rod 120 and the two lateral connecting rods 122 and 124. 124.

[0037] In each of the two embodiments presented here, the attachment mast 104 is completed by a rear arch 130 which has a part integral with the primary structure 106 and two arms which extend around the casing 112. The angular extension of the arms is generally equal to the angular extension of the extensions 108b, that is to say here 90° for the first embodiment and 180° for the second embodiment so as to form a rear ring.

[0038] The attachment mast 104 also comprises reinforcement bars with here first reinforcement bars 132 fixed between the extension 108b and the arm of the rear arch which is on the same side of the plane P and second reinforcement bars 134 fixed between the primary structure 1006 and each extension 108b and each arm.

Claims

1. Propulsion assembly (100) of an aircraft (50), said propulsion assembly (100) having a longitudinal axis (X) and a vertical median plane (P) passing through the longitudinal axis (X) and comprising: - a turbojet (102) comprising a casing (112) around the longitudinal axis (X) and a propeller (53) at the front of the casing (112), where the longitudinal axis (X) constitutes the axis of rotation of the propeller (53), - a suspension pylon (104) having a primary structure (106) and a front arch (108) having a central part (108a) integral with the primary structure (106) and on either side of the central part (108a) relative to the median plane (P), two extensions (108b) which extend around the casing (112) over at least 90°, - a connecting rod central (120) arranged at the level of the median plane (P),where the central connecting rod (120) has a rear end (120a) mounted articulated to the attachment mast (104) by a first rear connection point and a front end (120b) mounted articulated to the casing (112) by a first front connection point, - two lateral connecting rods (122, 124) arranged on either side of the median plane (P), where each inner connecting rod (122, 124) has a rear end (122a, 124a) mounted articulated to the extension (108b) which is on the same side of the median plane (P) by a second rear connection point and a front end (122b, 124b) mounted articulated to the casing (112) by a second front connection point and where the longitudinal axes of the lateral connecting rods (122, 124) and of the central connecting rod (120) converge on the longitudinal axis (X) at level of the center of the propeller (53), and - a rear engine attachment (150) fixing the primary structure (106) to a rear part of the casing (112)., 2. Propulsion assembly (100) according to claim 1,characterized in that the second front connecting points (122b, 124b) of the side connecting rods (122, 124) are arranged at 90°±20° around the longitudinal axis (X) from the first front connecting point of the central connecting rod (120).

3. Propulsion assembly (100) according to claim 1, characterized in that the second front connecting points (122b, 124b) of the side connecting rods (122, 124) are arranged at 130°±20° around the longitudinal axis (X) from the first front connecting point of the central connecting rod (120).

4. Propulsion assembly (100) according to one of claims 1 to 3, characterized in that it comprises a rear engine attachment (150) which ensures the attachment of the attachment mast (104) to a rear part of the casing (112).

5. Aircraft (50) comprising a wing (52) and a propulsion unit (100) according to one of the preceding claims, the primary structure (106) of which is fixed under the wing (52).

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